Voting (#3185)

* Basic voting

* Rewrite lobby in XAML.
Working lobby voting.

* Escape menu is now XAML.

* Vote menu works, custom votes, gamemode votes.

* Vote timeouts & administration.

Basically done now.

* I will now pretend I was never planning to code voting hotkeys.

* Make vote call UI a bit... funny.

* Fix exception on round restart.

* Fix some vote command definitions.

Content.Shared/Network/NetMessages/MsgVoteCanCall.cs

@@ -0,0 +1,32 @@
+using Lidgren.Network;
+using Robust.Shared.Network;
+
+namespace Content.Shared.Network.NetMessages
+{
+    /// <summary>
+    ///     Used to tell clients whether they are able to currently call votes.
+    /// </summary>
+    public sealed class MsgVoteCanCall : NetMessage
+    {
+        #region REQUIRED
+
+        public const MsgGroups GROUP = MsgGroups.Command;
+        public const string NAME = nameof(MsgVoteCanCall);
+
+        public MsgVoteCanCall(INetChannel channel) : base(NAME, GROUP) { }
+
+        #endregion
+
+        public bool CanCall;
+
+        public override void ReadFromBuffer(NetIncomingMessage buffer)
+        {
+            CanCall = buffer.ReadBoolean();
+        }
+
+        public override void WriteToBuffer(NetOutgoingMessage buffer)
+        {
+            buffer.Write(CanCall);
+        }
+    }
+}